The present invention relates to energy dissipators for motor vehicle safety belts.
It is known that in order to reduce the effects of crashes on the occupants of a motor vehicle, safety belts are used to absorb, at the moment of impact, part of the energy of the occupants. This energy can be dissipated by various methods. One method is to use belts in which plastic deformations take place or which yield under predetermined loads.
Another method of energy dissipation is to provide the ends of the belts with mechanical energy dissipators which absorb energy by various means, for example by friction, by plastic torsion of bars, or by flexure of metal bands or like elements. This second method is preferable to the use of plastically deformable belts since the belts themselves retain a suitable elasticity and, in the case of belts having elements of predetermined breaking-point, the load on the belt during impact varies considerably. Such energy dissipators can be included in the winding up devices with which safety belts are frequently provided.
In the event of impact it is necessary that the travel of the vehicle safety belt should be limited during the dissipation of energy, so that the occupant of the seat does not come into contact with parts of the vehicle passenger compartment facing him. This requirement is particularly important for safety belts used in small cars.
An object of the present invention is to provide a seat belt energy dissipator of simple and robust construction which allows the belt, during the dissipation of energy, to travel over a distance which can be predetermined by calibration using a calibration seat.